Technological development of devices which temporarily (a volatile memory) or semi-permanently (a non-volatile memory) store data by application of electrical or physical action on memory devices (also referred to as memories) provided in electronic devices has been active. In recent years, design of new memory devices aimed at price-reduction by improving function, miniaturization, or the like has also been actively developed. Note that a volatile memory refers to a memory device in which data is lost even after the data is held. In addition, a nonvolatile memory refers to a memory device in which data can be held semi-permanently after the data is held.
Among non-volatile memories, a ROM (read only memory), which performs only reading, is classified into a mask ROM and a PROM (programmable ROM). An EEPROM (electrically erasable and programmable read only memory), a fuse ROM, and an anti-fuse ROM belong to PROMs.
The mask ROM is a ROM to which information is written using a photomask or a laser direct drawing apparatus in a manufacturing process. The fuse ROM is a ROM in which a fuse which is in a conductive state at the time of manufacture is used for a memory element and the fuse is disconnected by current after the manufacture to make electrodes of the fuse electrically disconnected, whereby information is stored (hereinafter the fuse ROM is referred to as a fuse memory device). On the other hand, the anti-fuse ROM is a ROM in which an anti-fuse which is in a nonconductive state at the time of manufacture is used for a memory element and electrodes of the anti-fuse are electrically connected by current after the manufacture, whereby information is written thereto (hereinafter the anti-fuse ROM is referred to as an anti-fuse memory device). For example, Patent Document 1 discloses an anti-fuse memory device in which an anti-fuse memory element is electrically connected to a PN junction diode in series.
[Patent Document 1]
    Japanese Published Patent Application No. 2007-318104